[SOLVED] Max DC current for chokes

[Hatimoooo]

Hello everyone!

I'm having trouble finding high current and high inductance DC chokes. This is why I'm asking you this question about the max DC current for a choke.
If a choke can handle 200Amp DC current, does that mean that it can handle any waveform as long as it has an average value of 200Amps?
Thanks!

 

[FvM]

If a choke can handle 200Amp DC current, does that mean that it can handle any waveform as long as it has an average value of 200Amps?

No. Strictly spoken, there's a RMS current rating (calculated according to known scheme) and a saturation current. The saturation limit counts for instantaneous current. In addition, high AC currents (ripple current) might cause extra skin effect and core losses that must be considered by a derating.

What's "high inductance" for you?

 

[Hatimoooo]

Hello
Thanks for answering this fast.
The DC choke I'm looking for is around 200Amp and 0.5mH (more is better).
The signal I should be using is a rectified signal having an average value of 200Amp

I shouldn't worry about skin effect since I have low frequency harmonics

So high inductance is something around 0.5mH (for this current rating).
Thanks

 

[FvM]

For a size estimation http://www.emb-wittlich.com/ENGLISCH/Trafo_Daten/GD-GDS.HTM

Resulting weight is 26 kg.

 

[Hatimoooo]

Hello.
I didn't get any update about the subject.
Do I have to choose an inductor using the DC current, the rms and the max? The saturation current should be equal to the max current. Am I right?

 

[FvM]

An inductor designed for 200 A will have a certain margin for current ripple, so it will usually work for 200 A average with superimposed ripple. Also a low or medium ripple won't increase the total RMS current much.

The should be a L = f(I) saturation curve that allows to decide about acceptable peak current for your application.

 

[Hatimoooo]

Thanks a lot Mr FvM
I asked this question because my peak current can reach something like 300Amp, and this is not a small ripple.
I will ask inductor companies for these curves and hope to get them :-D.
Again, thanks a lot for your help. Much appreciated